Dish washer and method of controlling the same

ABSTRACT

Disclosed are a dish washer and a method of controlling the same, in which the amount of water consumed is reduced and a washing time is maintained while assuring a washing performance. The dish washer includes a washing tub; dish baskets provided in the washing tub to accommodate dishes; and a plurality of nozzles to spray washing water to the dish baskets, where spray holes to spray the washing water are formed through each of the plurality of nozzles, and the spray holes formed through the plurality of nozzles have areas different from one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2007-0030566, filed Mar. 28, 2007, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

The present invention relates to a dish washer and a method ofcontrolling the same, and more particularly, to a dish washer and amethod of controlling the same, in which the amount of water consumed isreduced while assuring a washing performance.

2. Description of the Related Art

Generally, dish washers are apparatuses that wash out contaminants(i.e., food waste, etc.) stuck to dishes by spraying cold or warmwashing water at a high pressure onto the dishes. Korean PatentLaid-open Publication No. 10-2005-0105721 discloses a dish washer.

The dish washer disclosed in the above Publication includes a washingtub to wash dishes supplied thereinto, a plurality of dish basketsprovided in multiple stages in the washing tub to receive the dishes,spray nozzles provided above and below the plurality of dish baskets tospray washing water, and a sump connected to the spray nozzles to pumpthe washing water to the spray nozzles.

In the above dish washer, when washing water is supplied to an inside ofthe washing tub under the condition that dishes to be washed are put inthe dish baskets, a circulation pump in the sump is operated to supplythe washing water to the spray nozzles, thus washing the dishes by thehigh injection pressure of the washing water. This washing process,including washing and rinsing steps, is divided into main modes,including a main washing mode and a last rinsing mode, and preliminarymodes, including a preliminary washing mode and a preliminary rinsingmode, and the modes are repeated four to six times according to courses.The temperature of the washing water and the time of each of the modesare determined according to the courses.

In the dish washer, an amount of the washing water required to operatethe circulation pump, which is needed by the spray nozzles, is suppliedin each of the modes. In the case that the amount of the washing waterrequired in each of the modes is 5 L, as the total number of the mainmodes and the preliminary modes in a standard course is four, thus 20 Lof the washing water is required. A criterion to calculate the energyrequired in the dish washer is the sum of the electric energy consumedby electric field products, such as the circulation pump, a heater,etc., during the course and the heat energy of temperature conversionefficiency in proportion to the amount of the washing water consumed.Accordingly, in order to reduce the energy, it is important to reducethe amount of the washing water consumed.

In order to reduce the amount of the washing water consumed for thepurpose of energy saving, a method in which a small-sized circulationpump and the number of spray holes of spray nozzles are reduced wasproposed. However, this method has several problems, such as thedeterioration of the washing performance of the dish washer due to theincrease of a portion of the inside of a dish washer, to which thewashing water is not sprayed, and the increase in washing time to obtaina desired washing performance of the dish washer.

SUMMARY

Therefore, one aspect of the embodiment is to provide a dish washer anda method of controlling the same, in which the amount of water consumedis reduced and a washing time is maintained while assuring a washingperformance.

Another aspect of the embodiment is to provide a dish washer and amethod of controlling the same, in which an area ratio of spray holes ofupper, middle, and lower nozzles is converted such that the amount ofwater sprayed from the middle nozzle is maximized, so as to increase awashing performance.

Yet another aspect of the embodiment is to provide a dish washer and amethod of controlling the same, in which the amount of water consumed inpreliminary modes carried out prior to main modes is decreased, todecrease the amount of water required in the entirety of the modes.

Additional aspects and/or advantages will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the invention.

The foregoing and/or other aspects are achieved by providing a dishwasher including a washing tub; dish baskets provided in the washing tubto accommodate dishes; and a plurality of nozzles to spray washing waterto the dish baskets, each of the nozzles having spray holes to spray thewashing water formed through each of the nozzles, the spray holes formedthrough the plurality of nozzles being size differently from one anotherand thus having areas different from one another for each of thenozzles.

The plurality of nozzles may include upper and lower nozzles installedabove and below the dish baskets and a middle nozzle installed betweenthe dish baskets, and the spray holes formed through the middle nozzlemay have an area larger than an area of the spray holes formed throughthe lower nozzle so that an amount of the washing water sprayed from themiddle nozzle is larger than an amount of the washing water sprayed fromthe lower nozzle.

The middle nozzle may have a first set of spray holes to spray thewashing water upwardly from the middle nozzle and a second set of sprayholes to spray the washing water downwardly from the middle nozzleformed there through.

The dish washer may further include a control unit to control a flow ofthe washing water supplied to the upper, middle, and lower nozzles, thecontrol unit setting an amount of the washing water in at least one modeout of a plurality of modes of washing the dishes with the washing waterto be smaller than an amount of the washing water in other modes of theplurality of modes.

The at least one mode may be a preliminary washing mode or a preliminaryrinsing mode.

The dish washer may further include a circulation pump to circulate thewashing water in the washing tub to guide the washing water to theupper, middle, and lower nozzles, and the control unit may control theupper and middle nozzles to spray the washing water by an operation ofthe circulation pump in the preliminary washing mode or the preliminaryrinsing mode.

A nozzle area ratio of the middle nozzle to the lower nozzle is 1.5 to1.

The foregoing and/or other aspects are achieved by providing a method ofcontrolling a dish washer having a washing tub, dish baskets provided inthe washing tub to accommodate dishes, a plurality of nozzles to spraywashing water to the dish baskets, and a heater to heat the washingwater, the method including supplying an amount of the washing water inat least one mode out of a plurality of modes of washing the dishes withthe washing water less than an amount of the washing water supplied inother modes of the plurality of modes.

The at least one mode may be a mode in which the heater is not operated.

The mode in which the heater is not operated may be a preliminarywashing mode or a preliminary rinsing mode.

The supply of the washing water may be controlled such that a level ofthe washing water in the washing tub is sensed, and when the sensedlevel is less than a predetermined low water level during an operationof the heater, the washing water is supplied to the washing tub.

The foregoing and/or other aspects are achieved by providing a method ofcontrolling a dish washer having upper, middle and lower nozzles and aheater, including supplying washing water only through the upper andmiddle nozzles in a modes in which the heater is not operated, an amountof the water supplied through the middle nozzle being greater than anamount of the water supplied through the upper and lower nozzles.

The washing water may be supplied through only the upper and middlenozzles in a preliminary washing mode or a preliminary rinsing mode, thepreliminary washing mode and the preliminary rinsing modes being modesprior to a main washing mode and a main rinsing mode, respectively.

The foregoing and/or other aspects are achieved by providing adishwasher, including: a plurality of nozzles including at least amiddle nozzle, the middle nozzle being provided at a middle portion ofthe dishwasher, the middle nozzle having a water supplying capacitygreater than that of a water supplying capacity of other nozzles of theplurality of nozzles.

The middle nozzle may have a plurality of spray holes formed therethrough having a larger area than an area of a plurality of spray holesformed through the other nozzles.

The plurality of nozzles may include an upper nozzle provided at anupper portion of the dishwasher, the middle nozzle supplying the wateronly with the upper nozzle in a preliminary washing mode or apreliminary rinsing mode, the preliminary washing and rinsing modesbeing modes prior to a main washing mode and a main rinsing mode,respectively.

The foregoing and/or other aspects are achieved by providing a method ofcontrolling a dishwasher having upper, middle and lower nozzles and aheater, the method including: supplying water through only the upper andmiddle nozzles in a preliminary washing mode or a preliminary rinsingmode, the preliminary washing and rinsing modes being modes prior to amain washing mode and a main rinsing mode, respectively; and supplyingwater through all of the upper, middle and lower nozzles in the mainwashing mode and a main rinsing mode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages will become apparent and morereadily appreciated from the following description of the embodiments,taken in conjunction with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view of a dish washer in accordancewith the present embodiment;

FIG. 2 is a control block diagram of a dish washer in accordance with anembodiment; and

FIGS. 3A to 3C are flow charts to illustrate a method of controlling adish washer in accordance with the present embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiment, an example ofwhich is illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout. The embodiment isdescribed below to explain the present invention by referring to theannexed drawings.

FIG. 1 is a longitudinal sectional view of a dish washer in accordancewith the present embodiment.

In FIG. 1, the dish washer of the present embodiment includes a mainbody 10 having a washing space formed therein, and a door 12 to open andclose the front surface of the main body 10. The main body 10 and thedoor 12 form the external appearance of the dish washer.

A washing tub 20 is provided in the main body 10. In the washing tub 20,upper and lower dish baskets 22 a and 22 b to accommodate dishes, racks24 a and 24 b slidably supporting the upper and lower dish baskets 22 aand 22 b, and upper, middle, and lower spray nozzles 26 a, 26 b, and 26c located above and below the dish baskets 22 a and 22 b to spraywashing water are provided.

The upper and middle spray nozzles 26 a and 26 b are connected to a sump42, which will be described later, by a first supply pipe 28 a, and thelower spray nozzle 26 c is connected to the sump 42 by the second supplypipe 28 b. Thereby, the washing water is supplied from the sump 42 tothe upper, middle, and lower spray nozzles 26 a, 26 b, and 26 c.

Here, the washing water supplied to the upper and middle spray nozzles26 a and 26 b through the first supply pipe 28 a and the washing watersupplied to the lower spray nozzle 26 c through the second supply pipe28 b are independently sprayed by an operation of the upper and middlespray nozzles 26 a and 26 b and an operation of the lower spray nozzle26 c. For this reason, a separated water flow converting device isprovided, or valves are respectively provided in the first and secondsupply pipes 28 a and 28 b.

The upper, middle, and lower spray nozzles 26 a, 26 b, and 26 c aredesigned such that the area ratio of spray holes of the upper, middle,and lower spray nozzles 26 a, 26 b, and 26 c to inject the washing wateris set to 0.5:1.5:1, for example, to maximize an amount of the washingwater sprayed from the middle spray nozzle 26 b. That is, the amount ofthe washing water sprayed from the middle spray nozzle 26 b is largerthan the amount of the washing water sprayed from the lower spray nozzle26 c, and thus it is possible to sufficiently carry out the preliminarywashing and preliminary rinsing of dishes accommodated in the lower dishbasket 22 b with the washing water sprayed downwardly from the middlespray nozzle 26 b and the falling water.

The middle spray nozzle 26 b is provided with a plurality of spray holesto upwardly spray the washing water and a plurality of spray holes todownwardly spray the washing water, thereby simultaneously spraying thewashing water upwardly and downwardly.

A heater 30 to heat the washing water is provided on the bottom of thewashing tub 20. The heater 30 is seated in a heater mounting groove 32formed in the bottom of the washing tub 20.

A machinery chamber 40 is prepared under the washing tub 20. The sump42, which collects and pumps the washing water supplied to the inside ofthe washing tub 20 to transfer the washing water to the upper, middle,and lower spray nozzles 26 a, 26 b, and 26 c, is provided in themachinery chamber 40, and a temperature sensor 44 to sense thetemperature of the washing water is installed in the sump 42.

Various channels and a circulation pump 46 to pump the washing water tothe channels are provided in the sump 42, and a drain pump 48 to drainthe contaminated washing water to the outside through a drain pipe 52and a drain valve 50 are provided at one side of the sump 42.

FIG. 2 is a control block diagram of a dish washer in accordance with anembodiment. In addition to the components, which are shown in FIG. 1,the dish washer further includes a water level sensing unit 58, an inputunit 60, a control unit 62, a driving unit 64, and a display unit 68.

The water level sensing unit 58 senses the amount (level) of water(washing water) supplied to the washing tub 20. The input unit 60 inputsvarious washing courses (for example, a standard course and a manualcourse) and operation data, such as a washing water temperature and theaddition of a rinsing mode, to the control unit 62 according to a user'sinstructions.

The washing courses include a standard course and a manual course. Inthe standard course, a water supplying mode to supply washing water, awashing mode to wash dishes by spraying the washing water onto thedishes after the water supplying mode, a heating mode to heat thewashing water to a temperature suitable to wash and rinse beforespraying the washing water onto the dishes, a draining mode to drain thewashing water to the outside after the washing mode, and a drying modeto dry the dishes after the washing mode are sequentially operated.Further, in the manual course, the respective modes, which are selectedaccording to conditions, are operated.

The control unit 62 is a microcomputer, for example, to operate the dishwasher according to the operation data inputted from the input unit 60to control the washing, rinsing, and drying modes. The control unit 62sets an amount of the washing water in preliminary modes, including apreliminary washing mode and a preliminary rinsing mode, in which theheater 30 is not operated, to be smaller than an amount of the washingwater in main modes, including a main washing mode and a last rinsingmode, in which the heater 30 is operated. For example, in the standardcourse, in the case that the amount of the washing water required ineach of the respective modes is a first water level (approximately 5 L),the above necessary amount (5 L) of the washing water is supplied ineach of the main modes, including the main washing mode and the lastrinsing mode, and an amount (i.e., 4 L, a second water level) of thewashing water that is smaller than the necessary amount of the washingwater by approximately 20% is supplied in each of the preliminary modes,i.e., the preliminary washing mode and the preliminary rinsing mode.Thereby, the total amount of the washing water consumed in the entiretyof the modes is reduced by approximately 10%.

In order to assure the washing performance of the dish washer, which maybe deteriorated due to the reduction of the amount of the washing waterconsumed, the control unit 62 carries out a circulation operation inwhich only the upper and middle spray nozzles 26 a and 26 b spray thewashing water in the preliminary modes, i.e., the preliminary washingmode and the preliminary rinsing mode. Thereby, dishes accommodated inthe lower dish basket 22 b are washed out by the washing water sprayedfrom the middle spray nozzle 26 b and the falling water.

The driving unit 64 drives the heater 30, the circulation pump 46, thedrain pump 48, the drain valve 50, a water supply valve 66, etc.according to driving control signals from the control unit 62. The watersupply valve 66 controls the supply of the washing water to the insideof the washing tub 20.

The display unit 68 displays the operating state and errors of the dishwasher according to a display control signal from the control unit 62.

Hereinafter, the operation and effects of the above dish washer and amethod of controlling the same will be described.

FIGS. 3A to 3C are flow charts to illustrate a method of controlling adish washer in accordance with the present embodiment.

When a user selects a washing course (for example, the standard course)and desired operation data under the condition that dishes to be washedare accommodated in the dish baskets 22 a and 22 b in the washing tub20, the operation data selected by the user is inputted to the controlunit 62 through the input unit 60.

Thus, the control unit 62 performs washing and rinsing modes accordingto the operation data inputted from the input unit 60. First, thecontrol unit 62 determines whether or not the washing course selected bythe user is a standard course (100).

When it is determined that the washing course selected by the user isthe standard course, the control unit 62 operates the water supply valve66 through the driving unit 64, and thus the washing water required inthe preliminary washing mode is supplied to the inside of the washingtub 20 (102). When it is determined that the washing course selected bythe user is not the standard course, the procedure returns to operation100.

Thereafter, the water level sensing unit 58 senses the amount of thewashing water supplied to the inside of the washing tub 20 in thepreliminary washing mode, and determines whether or not the sensedamount reaches the predetermined second water level (104). The amount ofthe washing water is smaller than the amount of the washing waterrequired in the main washing mode by approximately 20%, for example,approximately 4 L.

When it is determined that the sensed amount does not reach the secondwater level, the washing water is continuously supplied to the inside ofthe washing tub 20 until the sensed amount reaches the predeterminedsecond water level, and when it is determined that the sensed amountreaches the second water level, the control unit 62 switches off thewater supply valve 66, and thus the supply of the washing water isstopped (106).

The washing water supplied to the inside of the washing tub 20 iscollected in the sump 42 provided under the washing tub 20, and istransferred to the upper spray nozzle 26 a and the middle spray nozzle26 b through the first supply pipe 28 a by the pumping action of thecirculation pump 46 in the sump 42. Then, the upper and middle spraynozzles 26 a and 26 b spray the washing water onto the dishes havingcontaminants stuck thereto that are accommodated in the dish baskets 22a and 22 b at a high pressure. Thereby, the preliminary washing mode tomoisten the dishes and expand the contaminants stuck to the dishes isperformed (108).

In the preliminary washing mode, although the lower spray nozzle 26 c isnot operated and only the upper and middle spray nozzles 26 a and 26 bspray the washing water, since the area ratio of the spray holes of themiddle and lower nozzles 26 b and 26 c is approximately 1.5:1, thedishes accommodated in the lower dish baskets 22 b are sufficientlymoistened by the washing water sprayed through the middle spray nozzle26 b and the falling water.

When the preliminary washing mode is carried out, the control unit 62measures a time, and determines whether or not a predeterminedpreliminary washing time, approximately 15 minutes, for example haselapsed, i.e., whether or not the preliminary washing mode has beencompleted (110). When it is determined that the preliminary washing modehas not been completed, the procedure returns to operation 108, and thepreliminary washing mode is continuously carried out until thepreliminary washing time has elapsed.

As a result of the above determination, when it is determined that thepreliminary washing mode has been completed, since the contaminantsstuck to the dishes as well as the washing water are collected in thesump 42, the control unit 62 drains the washing water containing thecontaminants through the drain pipe 52 by the operations of the drainpump 48 and the drain valve 50 (112).

Thereafter, the control unit 62 operates the water supply valve 66 tocarry out the main washing mode after the preliminary washing mode, andthus the washing water required in the main washing mode is supplied tothe inside of the washing tub 20 (114).

The water level sensing unit 58 senses the amount of the washing watersupplied to the inside of the washing tub 20 in the main washing mode,and determines whether or not the sensed amount reaches thepredetermined first water level, which is the amount of the washingwater required in the main washing mode, i.e., approximately 5 L (116).

When it is determined that the sensed amount does not reach the firstwater level, the procedure returns to operation 114, and the washingwater is continuously supplied to the inside of the washing tub 20 untilthe sensed amount reaches the predetermined first water level, and whenit is determined that the sensed amount reaches the predetermined firstwater level, the control unit 62 switches off the water supply valve 66so that the supply of the washing water is stopped (118).

The washing water supplied to the inside of the washing tub 20 iscollected in the sump 42 provided under the washing tub 20 in the samemanner as the preliminary washing mode, and the washing water collectedin the sump 42 is heated to a predetermined temperature (approximately50°) by the heater 30 (120), and simultaneously a detergent is put intothe washing tub 20 through a detergent supply device (not shown).

Then, the warm washing water, having a temperature of approximately 50°,containing the detergent is transferred to the upper, middle, and lowerspray nozzles 26 a, 26 b, and 26 c through the first and second supplypipes 28 a and 28 b by the pumping action of the circulation pump 46 inthe sump 42. Then, the upper, middle, and lower spray nozzles 26 a, 26b, and 26 c spray the washing water onto the dishes accommodated in thedish baskets 22 a and 22 b at a high pressure. Thereby, the main washingmode to remove the contaminants from the dishes is performed (122).

In the main washing mode, all of the upper, middle, and lower spraynozzles 26 a, 26 b, and 26 c spray the washing water so that the washingwater is sprayed to the dishes to effectively remove the contaminantsfrom the dishes.

Further, in the main washing mode, when the sensed amount of the washingwater becomes less than a predetermined low water level during theoperation of the heater 30, the supply of the washing water is carriedout so that the amount of the washing water is not less than thepredetermined low water level.

When the main washing mode is carried out, the control unit 62 measuresa time, and determines whether or not a predetermined main washing time,approximately 30 minutes, for example, has elapsed, i.e., whether or notthe main washing mode has been completed (124). When it is determinedthat the main washing mode has not been completed, the procedure returnsto operation 122, and the main washing mode is continuously carried outuntil the main washing time has elapsed.

As a result of the above determination, when it is determined that themain washing mode has been completed in the same manner as thepreliminary washing mode, since the contaminants stuck to the dishes aswell as the washing water are collected in the sump 42, the control unit62 drains the washing water containing the contaminants through thedrain pipe 52 by the operations of the drain pump 48 and the drain valve50 (126).

Thereafter, the control unit 62 operates the water supply valve 66 tocarry out the preliminary rinsing mode after the main washing mode, andthus the washing water (specifically, rinsing water) required in thepreliminary rinsing mode is supplied to the inside of the washing tub 20(128).

The water level sensing unit 58 senses the amount of the washing water(rinsing water) supplied to the inside of the washing tub 20 in thepreliminary rinsing mode, and determines whether or not the sensedamount reaches the predetermined second water level (130). The amount ofthe washing water is smaller than the amount of the washing waterrequired in the main rinsing mode by approximately 20%, i.e.,approximately 4 L.

When it is determined that the sensed amount does not reach the secondwater level, the procedure returns to operation 128, and the washingwater (rinsing water) is continuously supplied to the inside of thewashing tub 20 until the sensed amount reaches the predetermined secondwater level. When it is determined that the sensed amount reaches thepredetermined second water level, the control unit 62 switches off thewater supply valve 66, and thus the supply of the washing water (rinsingwater) is stopped (132).

The washing water (rinsing water) supplied to the inside of the washingtub 20 is collected in the sump 42 in the same manner as the preliminarywashing mode and the main washing mode, and is transferred to the upperspray nozzle 26 a and the middle spray nozzle 26 b through the firstsupply pipe 28 a by the pumping action of the circulation pump 46 in thesump 42. Then, the upper spray and middle spray nozzles 26 a and 26 bspray the washing water widely onto the dishes at a high pressure.Thereby, the preliminary rinsing mode to wash off the contaminants andthe detergent fallen by the main washing mode is performed (134).

In the preliminary rinsing mode, although the lower spray nozzle 26 c isnot operated and only the upper and middle spray nozzles 26 a and 26 bspray the washing water, since the area ratio of the spray holes of themiddle and lower nozzles 26 b and 26 c is approximately 1.5:1, thedishes accommodated in the lower dish baskets 22 b are sufficientlyrinsed by the washing water sprayed through the middle spray nozzle 26 band the falling water.

When the preliminary rinsing mode is carried out, the control unit 62measures a time, and determines whether or not a predeterminedpreliminary rinsing time, approximately 5 minutes, for example, haselapsed, i.e., whether or not the preliminary rinsing mode has beencompleted (136). When it is determined that the preliminary rinsing modehas not been completed, the procedure returns to operation 134, and thepreliminary rinsing mode is continuously carried out until thepreliminary rinsing time has elapsed.

As a result of the above determination, when it is determined that thepreliminary rinsing mode has been completed, since the contaminants andthe detergent washed off by the washing water (rinsing water), as wellas the washing water (rinsing water) are collected in the sump 42, thecontrol unit 62 drains the washing water (rinsing water) containing thecontaminants and the detergent through the drain pipe 52 by theoperations of the drain pump 48 and the drain valve 50 (138).

Thereafter, the control unit 62 operates the water supply valve 66 tocarry out the last rinsing mode after the preliminary rinsing mode, andthus the washing water (rinsing water) required in the last rinsing modeis supplied to the inside of the washing tub 20 (140).

The water level sensing unit 58 senses the amount of the washing water(rinsing water) supplied to the inside of the washing tub 20 in the lastrinsing mode, and determines whether or not the sensed amount reachesthe predetermined first water level, which is the amount of the washingwater required in the main rinsing mode, i.e., approximately 5 L, forexample (142).

When it is determined that the sensed amount does not reach the firstwater level, the procedure returns to operation 140, and the washingwater (rinsing water) is continuously supplied to the inside of thewashing tub 20 until the sensed amount reaches the predetermined firstwater level. When it is determined that the sensed amount reaches thefirst water level, the control unit 62 stops the supply of the washingwater (rinsing water) (144).

The washing water (rinsing water) supplied to the inside of the washingtub 20 is collected in the sump 42 in the same manner as in thepreliminary rinsing mode, the washing water (rinsing water) collected inthe sump 42 is heated to a predetermined temperature (approximately 65°)by the heater 30 (146), and simultaneously a fabric softener is put intothe washing tub 20 through a softener supply device (not shown).

The warm washing water, having a temperature of approximately 60°, forexample, containing the fabric softener is transferred to the upper,middle, and lower spray nozzle 26 a, 26 b, and 26 c through the firstand second supply pipes 28 a and 28 b by the pumping action of thecirculation pump 46. Then, the upper, middle, and lower spray nozzles 26a, 26 b, and 26 c spray the washing water (rinsing water) onto thedishes accommodated in the dish baskets 22 a and 22 b at a highpressure. Thereby, the last rinsing mode to remove fine particles of thecontaminants from the dishes is performed (148).

In the last rinsing mode, all of the upper, middle, and lower spraynozzles 26 a, 26 b, and 26 c spray the washing water (rinsing water) sothat the washing water is sprayed to the dishes to effectively removethe fine particles of the contaminants from the dishes.

Further, in the last rinsing mode, when the sensed amount of the washingwater (rinsing water) becomes less than a predetermined low water levelduring the operation of the heater 30, the supply of the washing water(rinsing water) is carried out so that the amount of the washing water(rinsing water) is not less than the predetermined low water level.

When the last rinsing mode is carried out, the control unit 62 measuresa time, and determines whether or not a predetermined last rinsing time,approximately 30 minutes, for example, has elapsed, i.e., whether or notthe last rinsing mode has been completed (150). When it is determinedthat the last rinsing mode has not been completed, the procedure returnsto operation 148, and the last rinsing mode is continuously carried outuntil the last rinsing time has elapsed.

As a result of the above determination, when it is determined that thelast rinsing mode has been completed, since the contaminants stuck tothe dishes as well as the washing water (rinsing water) are collected inthe sump 42 in the same manner as in the preliminary rinsing mode, thecontrol unit 62 drains the washing water (rinsing water) containing thecontaminants through the drain pipe 52 by the operations of the drainpump 48 and the drain valve 50 (152).

Consequently, the total amount of the washing water consumed in thestandard course of the method of the present embodiment is 18 L, i.e.,the sum of 4 L in the preliminary washing mode, 5 L in the main washingmode, 4 L in the preliminary rinsing mode, and 5 L in the last rinsingmode. Thus, the amount of the washing water in the standard course ofthe method of the present embodiment is reduced by approximately 10%compared with the amount of the washing water (5 L×4=20 L) in thestandard course of the conventional method. Further, the increased areaof the spray holes of the middle spray nozzle 26 b prevents an increaseof a washing time and a deterioration of a washing efficiency due to thereduction of the amount of the washing water consumed. Moreover, theoperation of the lower spray nozzle 26 c is decreased, and thus, whenthe dish washer is used for a long period of time, the maintenance ofelectric field products is easily achieved.

As apparent from the above description, the present embodiment providesa dish washer and a method of controlling the same, in which the amountof water consumed is reduced and a washing time is maintained whileassuring a washing performance.

Further, the area ratio of spray holes of upper, middle, and lowernozzles is converted such that the amount of water sprayed from themiddle nozzle is maximized, so as to increase the washing performance.Moreover, the amount of water consumed in preliminary modes carried outprior to main modes is decreased, so as to reduce the amount of waterrequired in the entirety of the modes.

Although an embodiment has been shown and described, it would beappreciated by those skilled in the art that changes may be made in thisembodiment without departing from the principles and spirit of theinvention, the scope of which is defined in the claims and theirequivalents.

1. A dish washer, comprising: a washing tub; dish baskets provided inthe washing tub to accommodate dishes; and a plurality of nozzlesspraying washing water to the dish baskets, each of the nozzles havingspray holes spraying the washing water formed through each of thenozzles, the spray holes being sized differently from one another foreach of the nozzles.
 2. The dish washer according to claim 1, wherein:the plurality of nozzles includes upper and lower nozzles installedabove and below the dish baskets and a middle nozzle installed betweenthe dish baskets; and the spray holes formed through the middle nozzlehave an area larger than an area of the spray holes formed through thelower nozzle so that an amount of the washing water sprayed from themiddle nozzle is larger than an amount of the washing water sprayed fromthe lower nozzle.
 3. The dish washer according to claim 2, wherein themiddle nozzle has a first set of spray holes to spray the washing waterupwardly from the middle nozzle and a second set of spray holes to spraythe washing water downwardly from the middle nozzle formed therethrough.
 4. The dish washer according to claim 2, further comprising acontrol unit to control a flow of the washing water supplied to theupper, middle, and lower nozzles, the control unit setting an amount ofthe washing water in at least one mode out of a plurality of modes ofwashing the dishes with the washing water to be smaller than an amountof the washing water in other modes of the plurality of modes.
 5. Thedish washer according to claim 4, wherein the at least one mode is apreliminary washing mode or a preliminary rinsing mode.
 6. The dishwasher according to claim 5, further comprising a circulation pump tocirculate the washing water in the washing tub to guide the washingwater to the upper, middle, and lower nozzles, wherein the control unitcontrols the upper and middle nozzles to spray the washing water by anoperation of the circulation pump in the preliminary washing mode or thepreliminary rinsing mode.
 7. A method of controlling a dish washerhaving a washing tub, dish baskets provided in the washing tub toaccommodate dishes, a plurality of nozzles to spray washing water to thedish baskets, and a heater to heat the washing water, the methodcomprising: supplying an amount of the washing water in at least onemode out of a plurality of modes of washing the dishes with the washingwater less than an amount of the washing water supplied in other modesof the plurality of modes.
 8. The method according to claim 7, whereinthe at least one mode is a mode in which the heater is not operated. 9.The method according to claim 8, wherein the mode in which the heater isnot operated is a preliminary washing mode or a preliminary rinsingmode.
 10. The method according to claim 7, wherein the supply of thewashing water is controlled such that a level of the washing water inthe washing tub is sensed, and when the sensed level is less than apredetermined low water level during an operation of the heater, thewashing water is supplied to the washing tub.
 11. The dish washeraccording to claim 2, wherein a nozzle area ratio of the middle nozzleto the lower nozzle is 1.5 to
 1. 12. A method of controlling a dishwasher having upper, middle and lower nozzles and a heater, comprising:supplying washing water only through the upper and middle nozzles in amode in which the heater is not operated, an amount of the watersupplied through the middle nozzle being greater than an amount of thewater supplied through the upper and lower nozzles.
 13. The methodaccording to claim 12, wherein the washing water is supplied throughonly the upper and middle nozzles in a preliminary washing mode or apreliminary rinsing mode, the preliminary washing mode and thepreliminary rinsing modes being modes prior to a main washing mode and amain rinsing mode, respectively.
 14. A dishwasher, comprising: aplurality of nozzles including at least a middle nozzle, the middlenozzle being provided at a middle portion of the dishwasher, the middlenozzle having a water supplying capacity greater than that of a watersupplying capacity of other nozzles of the plurality of nozzles.
 15. Thedishwasher according to claim 14, wherein the middle nozzle has aplurality of spray holes formed there through having a larger area thanan area of a plurality of spray holes formed through the other nozzles.16. The dishwasher according to claim 14, wherein the plurality ofnozzles includes an upper nozzle provided at an upper portion of thedishwasher, the middle nozzle supplying the water only with the uppernozzle in a preliminary washing mode or a preliminary rinsing mode, thepreliminary washing and rinsing modes being modes prior to a mainwashing mode and a main rinsing mode, respectively.
 17. A method ofcontrolling a dishwasher having upper, middle and lower nozzles and aheater, the method comprising: supplying water through only the upperand middle nozzles in a preliminary washing mode or a preliminaryrinsing mode, the preliminary washing and rinsing modes being modesprior to a main washing mode and a main rinsing mode, respectively; andsupplying water through all of the upper, middle and lower nozzles inthe main washing mode and a main rinsing mode.